The trash talk has been going on for months but will this mouthwatering superfight get the green light. There are a lot of egos involved.

What are we talking about here?

A fight to end all fights between the undefeated, multi-weight American world champion boxer Floyd Mayweather, and Ireland's Conor McGregor - the only mixed martial arts man to hold belts in two divisions in the Ultimate Fighting Championship (UFC).

The face-off would be in the boxing ring, not the octagon; that would give Mayweather the initial advantage over McGregor, one would think.

When would it happen?

If it's going to happen it will surely not be too long now - there have already been months of hype about a potential Mayweather-McGregor match-up.

McGregor already got his licence to box back in December, so the two men would just have to go through training camps for the fight and we could be under way.

That said, if Mayweather were to come out of retirement, he would want to make sure he has trained as fully as he needs in order to be in peak condition for the fight.

Perhaps the best precedent is 'the fight of the century' between Manny Pacquiao and Mayweather himself, back in 2015.

When the bout was finally confirmed as official, fans had to wait less than three months for fight night. But that fight took the best part of a decade to put together, and negotiations are only really at the opening stages between Mayweather and McGregor.

Where would it happen?

McGregor was licensed to box by the US state of California at the end of 2016.

So Los Angeles is a more likely destination for the pair to clash than the popular Las Vegas, Nevada, just over the border.

What are the sticking points?

Money is one, of course - a big one.

Both fighters make quite a big deal of the financial benefits of their respective professions. Negotiations will be less about the money itself - both men are, evidently, fabulously wealthy already - and more about what the money represents. Neither man will want to lose face by giving away too much of what could be a gargantuan purse.

Mayweather has recently gone on record, saying the purse needs to be $100million and that he would offer McGregor $15million of that - with pay-per-view revenue to be divided later.

A photo posted by Conor McGregor Official (@thenotoriousmma) on Nov 23, 2016 at 9:48am PST

Mayweather's age must be taken into account in these negotiations. While McGregor is 28, Mayweather is 39 and any protracted negotiations are going to mean we won't be seeing Floyd take the ring with Conor until the former is in his forties.

Mayweather and his legion of followers have high expectations, and if the former champion can no longer do himself justice in the ring then he simply won't put himself there.

The American has a 49-0 record in professional boxing. While he may be sorely tempted to lunge for that 50th win, Mayweather has got to this point exactly by being rational and calculating. He won't risk his reputation lightly.

On McGregor's side, he has the UFC to worry about alongside anything he arranges with Mayweather.

The Irishman is already at loggerheads with the UFC chiefs who forced him to vacate his featherweight title, as he had not defended it for a little over a year.

If he absents himself again then McGregor could find his lightweight championship taken off him too. The UFC is where he has forged his name as one of the greatest mixed martial artists and whether he would be willing to jeopardise his career there in such a way remains to be seen.

What are they saying?

Floyd Mayweather

"Only thing I'm probably interested in is the Conor McGregor fight.

"I'm a businessman, and it makes business sense. I believe in what me and [adviser] Al Haymon talk about every day -- I believe in working smarter, not harder.

"We tried to make the Conor McGregor fight. They know what my number is. My number is a guaranteed $100m. That was my number.

"We are willing to give him $15m and then we can talk about splitting the percentage - the back end - on the pay-per-view.

"But of course, we're the 'A side.' How can a guy talk about making 20 or 30 million if he has never made 8 or 9 million in a fight."

Conor McGregor

In response to Mayweather's comments, McGregor tweeted a cartoon of himself defeating Mayweather. It carried a reference to the NBA player, C.J. Johnson, who Mayweather had alleged had a relationship with Josie Harris, the mother of three of his children, in 2010.

Mayweather was convicted of domestic abuse towards Harris in 2015. He was sentenced to two months in prison.

A photo posted by Conor McGregor Official (@thenotoriousmma) on Dec 24, 2016 at 2:44am PST

What are the chances of it happening?

Soon? Quite slim. But if clamour continues to grow then the sums of money involved might climb to irresistible levels.

The balance between waiting for the interest and the purse to inflate, and getting the fight done before Mayweather is too old to want to risk it, or go through another serious training camp - that's the key.